Biology subjects

Dhakal, S.

Publications and source records attributed to Dhakal, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Management of Root-Knot Nematode-Fusarium Wilt Complex with different Bio-management methods in Tomato (Solanum lycopersicum L.) var Srijana

The root-knot nematode-Fusarium complex is a major constraint to protected tomato cultivation in Nepal, particularly on the widely grown Srijana hybrid, which lacks Mi-mediated nematode resistance. The present study was conducted to identify the most effective biocontrol agent, to identify the most effective Solanum rootstock, and to compare the overall efficacy of grafting versus biocontrol agents under polyhouse conditions. For the management of the root knot nematode-Fusarium complex, a pot experiment was set up in a completely randomized design at Pokhara, Kaski. Treatments comprised Trichoderma viride, Pseudomonas fluorescens, their half-dose combination, self-grafted Srijana, and four resistant rootstocks (S. sisymbriifolium, S. melongena, S. torvum, and VNRRs-10), together with nematode-only, Fusarium-only, complex (Nematode + Fusarium), and disease-free controls. Each plant was inoculated with approximately 2,000 nematode eggs, followed by 25 ml of 10^6 spores per ml of Fusarium seven days later to mimic the field complex. Plant growth parameters and nematode infestation data were recorded and analyzed via RStudio v. 2026.04.0. The root knot nematode-Fusarium complex caused significantly greater reductions in vegetative biomass than root knot nematode and Fusarium alone (20.32 gm vs 38.40 gm vs 51.32 gm) at 45 DAT. Single-agent biocontrol gave intermediate protection (T. viride 64.9%; P. fluorescens 47.9% nematode management efficiency), whereas combined T. viride + P. fluorescens treatment produced the highest vegetative biomass but the weakest nematode suppression (320 galls, reproduction factor: 38). Grafting onto S. torvum and S. melongena resulted in the greatest nematode suppression, achieving 97.9% and 93.6% management efficiency, respectively, while S. torvum alongside VNRRs-10 maintained the highest Fusarium suppression (92.5%). Overall resistant rootstocks consistently outperformed biological control in reducing disease severity. These findings indicate that grafting onto resistant solanum rootstocks, particularly S. torvum and S. melongena, was observed as the most effective strategy for managing the root knot nematode-Fusarium complex under protected cultivation, offering a viable chemical-free management option. Keywords: Root-Knot Nematode, Fusarium oxysporum, RKN-Fusarium-complex, Solanum torvum

pathology↗

bioRxiv2026

A Modular Machine Learning Framework for Small-Molecule Drug Repurposing Based on Organ Permeability, Target Binding, and Biomarker Modulation

With nearly 90% of drug candidates failing in clinical trials due to poor efficacy or toxicity, drug repurposing has emerged as a vital strategy to accelerate the delivery of life-saving treatments. However, most current drug repurposing approaches fail to account for the physiological barriers and downstream biological impacts that dictate therapeutic success. To bridge this gap, we present SCOUT (Screening Candidates via Organ Uptake and Target-binding), a modular machine learning-driven framework for drug repurposing by simultaneously modeling organ permeability, drug-target binding, and biomarker modulation. Unlike conventional repurposing efforts that rely on single-point predictions or disconnected steps, SCOUT integrates these factors into a unified predictive funnel, significantly reducing trial-and-error and prioritizing candidates with the highest probability of therapeutic relevance. As a proof of concept, we applied SCOUT to Alzheimers disease, where blood-brain barrier (BBB) penetration is an important hurdle. The framework first predicts the unbound brain-to-plasma partition coefficient, Kpuu, using SMILES-based embeddings and achieved robust performance (Accuracy: 0.90, Recall: 0.94), then integrates machine learning to predict binding affinity with BACE1, a key Alzheimers target that was used in this work as a proof of concept. By combining these modules, SCOUT reduced the candidate search space by 99.9% and identified hits with diverse mechanisms of action. Critically, SCOUT extends beyond hit identification by employing mechanistic modeling to simulate how these candidates might modulate specific disease biomarkers (e.g. Amyloid-beta (A{beta}) peptides). This hybrid approach ensures repurposed candidates are not only chemically viable but also physiologically active, providing a rational and resource-efficient pipeline for drug development.

systems biology↗

bioRxiv2026

RfxCas13d Mediates Broad-Spectrum Suppression of Highly Pathogenic Avian Influenza

Highly pathogenic avian influenza viruses (HPAIVs) continue to cause substantial disease in birds and mammals, with repeated H5N1 spillovers highlighting the need for broadly protective antiviral strategies. Here we develop a programmable RNA-targeting antiviral platform based on RfxCas13d and evaluate its activity in avian cells. Screening of five Cas13 orthologs in chicken DF1 fibroblasts revealed RfxCas13d as the most potent and well tolerated effector. Virus-specific CRISPR RNAs (crRNAs) targeting conserved regions of positive- and negative-sense influenza RNA were tested against A/WSN/033[H1N1] and multiple HPAIV isolates, including a member of clade 2.3.4.4b H5N1. Targeting positive-sense RNA conferred superior influenza inhibitory activity and further enhanced by multiplexed crRNA expression. These findings establish RfxCas13d as a versatile RNA-guided antiviral platform and provide a route for broad-spectrum influenza control through conserved RNA targeting.

microbiology↗

bioRxiv2025

Biological Sex Differences after High and Low Doses of Influenza A Virus Infection in a Diet-induced Obesity Mouse Model

Obesity is an independent risk factor for influenza A virus (IAV) pathogenesis. In non-obese hosts, following IAV infection, adult females develop more severe disease than males. Limited research on biological sex differences following IAV infection in individuals with obesity forms the basis for this study. Male and female C57BL/6J mice were treated with high-fat or low-fat diets to obtain mice with or without obesity. They were inoculated intranasally with a high (103) or low dose (101.5 TCID50) of mouse-adapted A/California/04/2009 H1N1 IAV and followed for 21 days post-infection (dpi) for morbidity. Subsets of mice were euthanized at different dpi to measure lung virus titers, histopathological changes, cellular infiltration, and cytokine induction. After a high-dose infection, females with obesity demonstrated shorter median survival time, greater parenchymal inflammation, and heightened induction of inflammatory markers than males with obesity. After a low-dose infection, females than males, and mice with obesity than the non-obese mice, exhibited severe morbidity. Female mice with obesity exhibited the greatest disease severity, where 25% (2/8) reached humane endpoint. Delayed but persistent inflammatory changes were observed in females with obesity, characterized by relatively lower pathological changes, lesser induction of cytokines and chemokines, and reduced myeloid and lymphoid infiltration in the lungs at 3 dpi followed by sustained pathological changes and cytokine and chemokine induction at 21 dpi. Our study suggests that the biological sex difference following IAV infection persists during obesity. Females with obesity experience greater influenza disease severity than males, possibly driven by more severe dysregulation of inflammatory responses. ImportanceThe prevalence of obesity is increasing worldwide. The risk of developing severe disease following influenza virus infection is higher in individuals with obesity. Males and females with obesity differ in terms of fat deposition and inflammatory and metabolic biomarkers. These differences can alter the outcomes of influenza-induced disease pathogenesis. The observation of sex differences in IAV pathogenesis among non-obese hosts underscores the importance of determining whether similar differences occur in the context of obesity. Indeed, our study suggested that females with obesity experience greater disease severity than males with obesity after IAV infection. Understanding the immunological mechanisms of such differences will advance precision medicine approaches to develop safer and more effective preventive and therapeutic strategies against influenza for the high-risk populations with obesity.

immunology↗

bioRxiv2025

Females with Obesity Exhibit Greater Influenza Vaccine-induced Immunity and Protection than Males in a Mouse Model

IntroductionObesity is increasing globally, and it negatively impacts influenza vaccine efficacy. Although sex differences in influenza vaccine responses are studied in non-obese hosts, studies investigating sex differences in influenza vaccine-induced immunity and protection during obesity are limited. Materials and methodsUsing the C57BL/6J mouse model of high-fat diet (HFD)-induced obesity or low-fat diet controls, we investigated sex differences in influenza vaccine-induced immunity and protection during obesity. Male and female mice with or without obesity were vaccinated intramuscularly twice at a 3-week interval with an inactivated 2009 H1N1 influenza A virus (IAV) vaccine. At 35 days post-vaccination (dpv), antibody responses in plasma and B- and T-cell responses in spleen and bone marrow were quantified. At 42 dpv, mice were intranasally challenged with a drift variant of the H1N1 IAV, and disease severity was assessed by monitoring the change in body mass up to 21 days post-challenge (dpc). Subsets of mice were euthanized at 3 dpc to determine pulmonary virus replication (TCID50 assay), histopathology (H&E staining), and cytokine/chemokine responses (multiplex ELISA). ResultsFemale mice, irrespective of diet and obesity status, developed higher antibody responses and were better protected compared to males. Vaccinated males with obesity mounted the poorest antibody responses, experienced a more severe disease, were unable to clear replicating virus from the lungs effectively, and demonstrated heightened pulmonary inflammation. Despite these differences, splenic B- and T-cell frequencies were comparable, suggesting the inefficiency of B cells to produce antibodies in males but not in females with obesity. DiscussionOur findings suggest that sex differences is observed in influenza vaccine-induced immunity and protection during obesity, where males are more severely affected. These findings highlight the importance of considering biological sex and obesity status in influenza vaccine design and testing.

immunology↗

bioRxiv2025

BMP and NODAL Paracrine Signalling Regulate the Totipotent-like Cell State in Embryonic Stem Cells.

1)Cell-cell communication coordinates signalling between cells to guide context-dependent cell fate decisions such as proliferation, differentiation, and lineage specification. Such communication mechanisms are poorly understood in regulating the stem cell states. In this study, we investigate how cell-cell communication regulates cell fate transitions in heterogeneous embryonic stem cell populations, with a particular focus on totipotent-like cells that resemble the two-cell stage embryo. Using single-cell RNA sequencing in combination with computational frameworks, we map ligand- receptor interactions and model downstream regulatory effects across various stem cell states. We functionally validate the predictions by selectively perturbing signalling pathways under specific culture conditions. Our data reveal the key roles of BMP and NODAL (TGF-{beta}) signalling in mediating intercellular communication to shape stem cell identity and heterogeneity. These findings enhance our understanding of the signalling logic that governs early developmental cell fate decisions, providing new insights into stem cell biology with broad implications for regenerative medicine and developmental modelling.

cell biology↗

bioRxiv2025

Induction of cellular totipotency by NACC1-driven feed-forward regulation.

Mammalian embryo development begins with totipotent cells. Despite its significance, gene regulatory mechanisms controlling the totipotent cell stage are poorly understood. Based on single-cell proteomics and transcriptomics, we identified nucleus accumbens-associated 1 (NACC1) as a critical regulator of totipotent-like cell state in mouse embryonic stem cells. Using a combination of genomics approaches, we found that NACC1 directly binds to gene-regulatory regions and favours chromatin accessibility to induce the expression of totipotency and zygotic genome activation genes, as well as retrotransposons associated with totipotency. In parallel, NACC1-regulated retrotransposons further modulate the expression of proximal totipotency genes, forming a coherent feed-forward mechanism that regulates totipotent-like cells. Furthermore, NACC1 is crucial for the progression of embryogenesis beyond the totipotency stage. Thus, we uncover a genome-level NACC1-driven feed-forward gene regulatory mechanism that governs totipotent-like cells and has a crucial role during embryonic development.

developmental biology↗

bioRxiv2025

United we stand: Plants that physically touch each other are more resilient to stress

Plants use sophisticated signaling networks to communicate with each other. While this process is thought to support the overall health and resilience of plant communities, it could also reflect eavesdropping between plants used for competition. Here we reveal that plants that physically touch each other aboveground are more resilient to excess light stress, and that this phenomenon is dependent on the ability of plants to exchange aboveground electric and H2O2 signals with each other. Using a mutant that is unable to transfer Ca2+/reactive oxygen species (ROS) signals but can transfer electric signals (hpca1), as a mediator/connector between different plants, we further separate electric from Ca2+/ROS plant-to-plant signals and transcriptional landscapes, and show that the transfer of Ca2+/ROS signals, as well as the function of several Ca2+/ROS-dependent transcripts, is required for excess light stress acclimation. Our study reveals that plants that live together and physically touch each other establish an aboveground community-wide signaling network that enhances their collective resilience to stress. TeaserPlants that physically touch and exchange aboveground signals with each other are more resilient to excess light stress.

plant biology↗

bioRxiv2025

Modifications of the 22A apoA-I mimetic peptide sequence improve the anti-atherosclerotic properties of synthetic HDL

Synthetic high-density lipoprotein (sHDL) constituted of apolipoprotein A-I (apoA-I) mimetic peptides and phospholipids are nanometer-scale particles designed to recreate biological functions of HDL particles in the context of cardiovascular disease. Particularly, the therapeutic efficacy of sHDL particles is attributed to their ability to promote reverse cholesterol transport (RCT), a process where accumulated cholesterol is transported from peripheral tissues to the liver for elimination. Here, we designed two novel apoA-I mimetic peptides (22A-F and 22A-P-18A) by modifying the sequence of the well-studied apoA-I mimetic peptide 22A. These modifications were intended to improve cholesterol efflux from macrophages in vitro and structural stability of sHDL particles in human plasma while preserving their ability to activate lecithin-cholesterol acyltransferase (LCAT). We performed a systematic examination of the potency of sHDL particles made with these peptides in cellular cholesterol efflux, activation of LCAT, plasma HDL remodeling and proteolytic stability. Our study highlights that these modifications improve cholesterol efflux and, in the case of 22A-P-18A, also cholesterol esterification rate by LCAT but they do not appear to influence HDL remodeling in human plasma. Nonetheless, the LCAT activity assay conducted in human plasma suggest that intact sHDL particles are present and are likely the primary contributors to the increased cholesterol esterification rate, rather than the pre-{beta} HDL fraction generated through HDL remodeling. These findings offer new mechanistic insights into how specific peptide modifications affect key steps in RCT, laying the groundwork for future studies to explore their functional relevance in atherosclerosis and HDL-based drug delivery applications.

pharmacology and toxicology↗

bioRxiv2025

Transcriptomic and physiological responses of soybean plants subjected to a combination of water deficit and heat stress under field conditions

Water deficit, heat stress, and a combination of water deficit and heat stress are highly disruptive to crop yield worldwide. Unfortunately, the frequency and intensity of these conditions is gradually increasing due to climate change. Previous studies of water deficit and heat stress combination were primarily conducted under controlled growth conditions, revealing that the combination of water deficit and heat stress resulted in the activation of unique stress responses and acclimation pathways. However, whether similar responses to stress combination occur in the field remained largely unknown. Here we report on a two-year field study in which the transcriptomic and physiological responses of vegetative and reproductive tissues of soybean (Glycine max) to water deficit, heat treatment and their combination were studied. Our findings reveal that the transcriptomic responses of soybeans grown in the field are different from those grown under controlled growth chamber conditions. These differences were especially noticeable in plants subjected to the heat or water deficit treatments, and less in plants subjected to the stress combination. In addition, we report that differential transpiration between leaves and pods, that was originally discovered in plants grown under controlled growth conditions, occurs in field grown soybeans in response to heat stress, as well as heat stress combined with water deficit. We hope that the transcriptomic datasets generated by our study will contribute to future studies of crop responses to different stresses in the field, as well as highlight the need for more omics studies of plants grown under field conditions.

plant biology↗

bioRxiv2025

Transmembrane channel-like proteins regulate crop size and contraction dynamics during Drosophila feeding

Feeding regulation in Drosophila involves complex interactions between mechanosensory and neuroendocrine pathways. Our study identified transmembrane channel-like (TMC) proteins as key regulators of crop size and contraction, functioning through distinct neuronal populations. They influence crop size via diuretic hormone, Dh44-expressing neuroendocrine cells in the pars intercerebralis (PI) region and regulate crop contraction through the serotonin receptor 5-HT7. We found that TMC proteins are broadly expressed from the gut to the brain, reinforcing their role in the brain-gut axis. Mechanotransduction channels, including NompC, Piezo, and TMC, facilitate food ingestion, with TMC channels playing an additional role in food storage and transport. We noted the coexpression of piezo with Dh44 in only two neurons, indicating that at least two Dh44 cells are required for crop size regulation. Moreover, we identified Dh44R2 as the key receptor regulating crop size. Unlike DH44 and Piezo, TMC, 5-HT7, and TRP{gamma} are essential for crop contraction, suggesting that these channels serve as therapeutic targets for regulating food intake. Our findings also support the involvement of a mechanosensory serotonergic pathway in regulating crop physiology, integrating sensory and neuroendocrine signals to control food storage and transport. These findings advance our understanding of the neuronal and molecular mechanisms underlying feeding behavior in Drosophila and provide a foundation for exploring conserved pathways that regulate food intake in other organisms, including mammals.

physiology↗

bioRxiv2024

TRPg regulates lipid metabolism through Dh44 neuroendocrine cells

Understanding how the brain controls nutrient storage is pivotal. Transient receptor potential (TRP) channels are conserved from insects to humans. They serve in detecting environmental shifts and in acting as internal sensors. Here, we found that a TRP{gamma} mutant exhibited in Drosophila melanogaster are required for maintaining normal lipid and protein levels. In animals, lipogenesis and lipolysis control lipid levels in response to food availability. Lipids are mostly stored as triacylglycerol in the fat bodies (FBs) of D. melanogaster. Interestingly, trp{gamma} deficient mutants exhibited elevated TAG levels and our genetic data indicated that Dh44 neurons are indispensable for normal lipid storage but not protein storage. The trp{gamma} mutants also exhibited reduced starvation resistance, which was attributed to insufficient lipolysis in the FBs. This could be mitigated by administering lipase or metformin orally, indicating a potential treatment pathway. Gene expression analysis indicated that trp{gamma} knockout downregulated brummer, a key lipolytic gene, resulting in chronic lipolytic deficits in the gut and other fat tissues. The study also highlighted the role of specific proteins, including neuropeptide DH44 and its receptor DH44R2 in lipid regulation. Our findings provide insight into the broader question of how the brain and gut regulates nutrient storage.

genetics↗

bioRxiv2023

Estradiol Mediates Greater Germinal Center Responses to Influenza Vaccination in Female than Male Mice

Adult females of reproductive ages develop greater antibody responses to inactivated influenza vaccine (IIV) than males. How sex, age, and sex steroid changes impact B cells and durability of IIV-induced immunity and protection over 4-months post-vaccination (mpv) was analyzed. Vaccinated adult females had greater germinal center (GC) B cell and plasmablast frequencies in lymphoid tissues, higher neutralizing antibody responses 1-4 mpv, and better protection against live H1N1 challenge than adult males. Aged mice, regardless of sex, had reduced B cell frequencies, less durable antibody responses, and inferior protection after challenge than adult mice, which correlated with diminished estradiol among aged females. To confirm that greater IIV-induced immunity was caused by sex hormones, four core genotype (FCG) mice were used, in which the testes determining gene, Sry, was deleted from ChrY and transferred to Chr3, to separate gonadal sex (i.e., ovaries or testes) from sex chromosome complement (i.e., XX or XY complement). Vaccinated, gonadal female FCG mice (XXF and XYF) had greater numbers of B cells, higher antiviral antibody titers, and reduced pulmonary virus titers following live H1N1 challenge than gonadal FCG males (XYM and XXM). To establish that lower estradiol concentrations cause diminished immunity, adult and aged females received either a placebo or estradiol replacement therapy prior to IIV. Estradiol replacement significantly increased IIV-induced antibody responses and reduced morbidity after the H1N1 challenge among aged females. These data highlight that estradiol is a targetable mechanism mediating greater humoral immunity following vaccination among adult females. ImportanceFemales of reproductive ages develop greater antibody responses to influenza vaccines than males. We hypothesized that female-biased immunity and protection against influenza was mediated by estradiol signaling in B cells. Using diverse mouse models ranging from advanced age mice to transgenic mice that separate sex steroids from sex chromosome complement, those mice with greater concentrations of estradiol consistently had greater numbers of antibody producing B cells in lymphoid tissue, higher antiviral antibody titers, and greater protection against live influenza virus challenge. Treatment of aged female mice with estradiol enhanced vaccine-induced immunity and protection against disease, suggesting that estradiol signaling in B cells is critical for improved vaccine outcomes in females.

immunology↗

bioRxiv2023

A single pair of pharyngeal neurons functions as a commander to reject high salt in Drosophila melanogaster

Salt is an essential nutrient for survival, while excessive NaCl can be detrimental. In the fruit fly, Drosophila melanogaster, internal taste organs in the pharynx are critical gatekeepers impacting the decision to accept or reject a food. Currently, our understanding of the mechanism through which pharyngeal gustatory receptor neurons (GRNs) sense high salt are rudimentary. Here, we found that a member of the ionotropic receptor family, Ir60b, is expressed exclusively in a pair of GRNs activated by high salt. Using a two-way choice assay (DrosoX) to measure ingestion volume, we demonstrate that IR60b and two coreceptors IR25a and IR76b, are required to prevent high salt consumption. Mutants lacking external taste organs but retaining the internal taste organs in the pharynx exhibit much higher salt avoidance than flies with all taste organs but missing the three IRs. Our findings highlight the vital role for IRs in a pharyngeal GRN to control ingestion of high salt.

neuroscience↗

bioRxiv2023

α-Synuclein emulsifies TDP-43 prion-like domain - RNA liquid droplets to promote heterotypic amyloid fibrils

Many neurodegenerative diseases including frontotemporal lobar degeneration (FTLD), Lewy body disease (LBD), multiple system atrophy (MSA), etc., show colocalized deposits of TDP-43 and -synuclein (S) aggregates. To understand whether these colocalizations are driven by specific molecular interactions between the two proteins, we previously showed that the prion-like C-terminal domain of TDP-43 (TDP-43PrLD) and S synergistically interact to form neurotoxic heterotypic amyloids in homogeneous buffer conditions. However, it remains unclear whether and how S modulates TDP-43 present within liquid droplets and biomolecular condensates called stress granules (SGs). Here, using cell culture and in vitro TDP-43PrLD - RNA liquid droplets as models along with microscopy, nanoscale spatially-resolved spectroscopy, and other biophysical analyses, we uncover the interactions of S with phase-separated droplets. We learn that S acts as a Pickering agent by forming clusters on the surface of TDP-43PrLD - RNA droplets and emulsifying them. The hardening of the droplets that follow by S aggregates on the periphery, nucleates the formation of heterotypic TDP-43PrLD amyloid fibrils with structures distinct from those derived from homogenous solutions. Together, these results reveal an intriguing property of S as a Pickering agent in interacting with SGs and unmask the hitherto unknown role of S in modulating TDP-43 proteinopathies.

biophysics↗

bioRxiv2022

Extraction and characterization of cellulose from invasive weeds from central Nepal: A potential prospect of environmental management.

The cellulose is made up of long chains of polysaccharide of glucose molecules. Microfibrils are formed when numerous hydrogen-bonded cellulose chains unite, they are extremely stiff and contribute to physical stability, due to this general ability of forming these microfibrils to form long chains, cellulose is an ideal molecule for the manufacturing of packaging materials and bioplastics. On the other hand, Invasive plant species are one of the major constituents for environmental degradation and its application seems outmost. The main purpose of this study is to extract and identify the composition of cellulose fiber and characterize the fiber of invasive plant species that could be used as a replacement for plastics and textiles in some cases. In this study, Cellulose was isolated from 6 invasive species collected in Nepals Ramechhap district using various techniques, the composition of the fiber was identified using AOAC method 973.18, ASTM method D1106-96 and ASTM method E1755-01 and characterized using FTIR spectroscopy with weight analyses. Acid hydrolysis, chlorination, alkaline extraction, and bleaching were among the chemical methods adopted. In all of the samples, there were two primary absorbance peaks. The first occurred at low wavelengths in the 700-1,800 cm-1 range, while the second occurred at higher wavelengths in the 2,700-3,500 cm-1 range.The percentage of lignin within the final sample was determined in the range of 4.4-3.1% and the percentage yield of cellulose was determined within the range of 78-62%.The study shows that the cellulose can be extracted from the taken invasive plant species and can be used for further applications.

biochemistry↗

bioRxiv2022

Distinct neurotoxic TDP-43 fibril polymorphs can be generated by heterotypic interactions with α-synuclein

Amyloid aggregates of specific proteins form important pathological hallmarks in many neurodegenerative diseases, defining neuronal degeneration and disease onset. Recently, increasing numbers of patients show co-morbidities and overlaps between multiple neurodegenerative diseases, presenting distinct phenotypes. Such overlaps are often accompanied by co-localizations of more than one amyloid protein, prompting the question of whether direct interactions between different amyloid proteins could generate heterotypic amyloids. To answer this question, we investigated the effect of -synuclein (S) on TDP-43 aggregation inspired by their co-existence in pathologies such as Lewy body dementia and limbic predominant age-related TDP-43 encephalopathy. We previously showed that S and prion-like C-terminal domain (PrLD) of TDP-43 synergistically interact with one another to generate toxic heterotypic aggregates in vitro. Here, we extend these studies to investigate whether S induces structurally and functionally distinct polymorphs of PrLD aggregates. Using S -PrLD heterotypic aggregates generated in two different stoichiometric proportions, we show that S can effect PrLD fibril forms. The fibril samples have distinctive residue-level structural signatures in NMR spectra, dye-binding capability, proteinase K (PK) stability, and SDS-sensitive thermal stability. By gold nanoparticle labeling and TEM, we show the presence of both S and PrLD proteins within the same fibrils, and thus the existence of hetertypic hybrid fibrils. We also observe that S and PrLD co-localize in the cytosol of SH-SY5Y neuroblastoma cells, and show that the heterotypic PrLD fibrils selectively induce synaptic dysfunction in primary cortical neurons. These findings establish the existence of heterotypic amyloid polymorphs and provide a molecular basis for the observed overlap between synucleinopathies and TDP-43 proteinopathies.

biophysics↗

bioRxiv2022

Greater breadth of vaccine-induced immunity in females than males is mediated by increased antibody diversity in germinal center B cells

Inactivated influenza vaccines induce greater antibody responses in females than males among both humans and mice. To test the breadth of protection, we used recombinant mouse-adapted A/California/2009 (maA/Cal/09) H1N1 viruses containing mutations at one (1M), two (2M), or three (3M) antigenic sites, in addition to a virus containing the 1M mutation and a substitution of the Ca2 antigenic site (Sub) with one derived from an H5 hemagglutinin (HA) to challenge mice of both sexes. Following maA/Cal/09 vaccination, females produced greater virus-specific class-switched IgG and IgG2c antibodies against the vaccine and all mutant viruses, and antibodies from females recognized more unique, linear HA epitopes than antibodies from males. While females had greater neutralizing antibody (nAb) titers against the vaccine virus, both sexes showed lower neutralization capacity against mutant viruses. After virus challenge, vaccinated females had lower pulmonary virus titers and reduced morbidity than males against the 1M and 2M viruses, but not the Sub virus. Females generated greater numbers of germinal center (GC) B cells containing superior somatic hypermutation frequencies than vaccinated males. Deletion of activation-induced cytidine deaminase (Aicda) eliminated female-biased immunity and protection against the 2M virus. Harnessing methods to improve GC B cell responses and frequencies of somatic hypermutations, especially in males, should be considered in the development of universal influenza vaccines. SummaryCompared with males, inactivated influenza vaccination of female mice causes greater production of class-switched, somatically-hypermutated antibodies and a more robust germinal center B cell response, leading to more diverse H1N1 antigen recognition and better protection against mutant influenza A viruses.

immunology↗